1. Field of Invention
The present invention relates to electro-optical apparatuses, image processing circuits, image data correction methods, and electronic apparatuses, in which nonuniformity of luminance, nonuniformity of color, and the like are suppressed.
2. Description of the Related Art
A conventional electro-optical apparatus is, for example, an active matrix liquid crystal display apparatus primarily formed of a liquid crystal panel, an image signal processing circuit, and a timing generating circuit. Among these elements, the liquid crystal panel is formed of a pair of substrates with a liquid crystal provided therebetween. Specifically, of the pair of substrates, one substrate is provided with a plurality of scanning lines and a plurality of data lines, in which the scanning lines and the data lines intersect each other and are electrically insulated from each other. At each of these intersections, a pair of a thin film transistor (hereinafter referred to as a “TFT”), which is an example of a switching device, and a pixel electrode is provided. The other substrate is provided with transparent counter electrodes (common electrodes) opposing the pixel electrodes. Hence, the liquid crystal display panel is maintained at a constant potential.
Opposing surfaces of the two substrates are provided with alignment layers, which are rubbed so that liquid crystal molecules are continuously twisted approximately 90 degrees in the major axis direction between the two substrates. Back surfaces of the two substrates are provided with polarizers in accordance with the alignment direction. With this arrangement, light passing through the pixel electrode and the counter electrode is rotated approximately 90 degrees along the twisting of the liquid crystal molecules when the effective value of a voltage applied across the two electrodes is zero. In contrast, as the voltage effective value increases, the liquid crystal molecules become tilted in the electric field direction, and hence the optical activity is lost. For example, in the transmissive type, when polarizers, in which their polarization axes meet at right angles in accordance with the alignment direction, are arranged on the incidence side and on the back side (in the case of a normally white mode), and when the effective value of the voltage applied across the electrodes is zero, the transmissivity reaches a maximum (white is displayed). In contrast, as the effective value of the voltage applied across the two electrodes increases, light is blocked and the transmissivity reaches a minimum (black is displayed).
In addition, the timing generating circuit outputs timing signals used by each component. The image signal processing circuit performs gamma correction processing, which is performed by converting image data input to a liquid crystal display device into voltage information corresponding to the gray scale value of the image data in accordance with transmissivity (or reflectivity) characteristics relative to the effective value of the voltage applied across the pixel electrode and the counter electrode. In general, the gamma correction processing is often performed by using a table storing a relationship between the input image data and the corrected image data.
Concerning an actual liquid crystal panel, liquid crystal layers are not uniform in thickness, and operating characteristics of the TFTs on the surfaces vary widely. For these reasons, nonuniformity of luminance occurs. Concerning techniques to decrease the nonuniformity of luminance, there is a technique in which a display region is appropriately divided into blocks, and tables are switched for the block units (for example, see Japanese Unexamined Patent Application Publication No. 3-18822).
Concerning such a technique, there is a technique in which, instead of preparing tables for all blocks, tables are prepared for predetermined blocks. For a block for which a table is not prepared, interpolation processing is performed based on tables for the neighboring blocks, and a table for that block is thus generated. Accordingly, the memory capacity required for the tables is reduced (for example, see Japanese Unexamined Patent Application Publication No. 5-64110).